Art of pipe-thread formation.



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ART oF PIPE THREAD FORMATION.

APPLICATION FILED IAB. 17. 1906.

- 2 SHEETS-SHEET 1. 302966 me PATENTED JULY 9. 1907. c. L. cUMMINGs. ART 0F PIPE THREAD FORMATION.

APPLIUATIOI FILED IAB. 17. 1906.

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`York and State of UNITED STATES PATENT.

CHARLES VL. OUMMINGS, OF NEW YORK, N. Y.,\AsSIGNOR To CUMMINGS MACHINE COMPANY,

OENEW YORK, N. Y., A ooRPohATIoN OF NEW YORK. l

ART F PIPELTHREAD FORMATION.

Specification of Letters Patent.

Patented July 9. 1907;

Application filed March 17, 1906. Serial No. 306,508.

To all 'whom tt may concern.'

Be it known that '1, CHARLES L. GUMMINos, a citizen of the United States, yresiding in the city of New York, borough of Manhattan, in the county of New New York, have invented certain new and useful Improvements in the Art of Pipe- Thread Formation, of which the following is a speciication.

This invention relates t0 the art of pipe thread' formation, and has forr an object to provide an improved method or process of forming pipe threads upon metal tubing, and` is peculiarly adapted for forming bya forging or analogous -treatment such threads upon tubing having-comparatively thin walls.

One form of screw thread now known as a standard taper pipe thread has its face at about sixty degrees and the outside ofthe threaded tube endmay be tapered at about the ratio'of three-quarters of an inch to the foot, and the present improvement in the art4 presents an improved mode of production having in view an improved product, which product is set forth.4

in my concurrently pending application Serial N o. 308,464, filed March 28th 1906.

ln producing thread formation according to these present improvements the operation may best be commenced at a point inward of the end of the tubing 'and the operation proceeded with step by step toward suchzend', the metal being gradually forged-.up and caused to ow into position for formingproper screw threads without weakening the tube or materially altering the radial thickness of the walls thereof, -par ticularly at the bottom of the thread forming groove, and when the taper effect is desired the wall 0f the tube will be tapered. The thread produced will be disposed in a conical helix, the convolutions 0f the thread gradually decreasing in diameter toward the end of the tube.

l t is well known that the method which now exists for cutting screw threads upon tubing by nieansof dies weakens the tubing, in thatl the bottom of nthe thread forming groove approachestoward the inner face oi the tube wall and as the outer diameter oi the tube is reduced due to the taper given the threaded end, the inner diameter remaining unchanged, the bottom of the groove gradually enters the metal to such an extent and cuts away so much metal that it is impossible to put standard pipe threads, which of the requirements of its use may demand, so that after the cutting away of the tubing in making the thread forming groove it shall at such regions have sufiicient strength to withstand strains and pressures to which the tubing is to be subjected. By my present improvement it is feasible to produce threads of a height radially approaching and even greater than the radial thickness of the tube, and to do this without reducing the tensile or the bursting strength of` the tube. In the production ofthe thread, the tube will be worked upon and subjected to forging treatment, .that is a treatment causing viiowage of the metal or an active molecular redistribution, from and upon the outer and the inner sidescontemporaneously at the same region of the thread being-formed. r Working or'forg- 'ing pressure will be applied to the .outer side of the tubingto forge-up the metal or for forming the same by flowage into the shape of the, desiredv thread, and

co-operative working or forging pressure will at the lsame time be carried on upon the inner side ofthe same portion of the tube wall. Each portion may be subjected to a series of such working-treatments, these being independently but successively applied, and the entireowage and building up will be the net result of a plurality of distinct forging actions. The metal for constituting the thread will be engaged at points upon opposite sides of such thread, that is engaging opposite side Vfaces thereof and pressing the metal so that this is caused to flow in a radial direction, both toward and from the axis of the tube. The

flowing away action of the metal will be for building up the' thread and for completing the apex thereof,

Vand counter pressure will be applied to the metal to force portions of this in the opposite direction andl inwardly of the tube at a point below the bottom of 90 the thread forming groove, so that the metal will be forged and a owage set up toward, beyond and about the region of the bottom of the groove for building up the metal'an'dcompensating for the displacement at such region du'e to the forging action upon the metal' 95 at the bottom of the groove. When reference is made to the metal flowing in a direction away from the axis of the tube, the fact is not lost sight of that the portion of the tube wall being acted upon is trans' lated, as it were, toward the axis, and also in such `1,00

and after its translation,

translated portion, during the molecular owage is taking place in. different l radial and other directions. In fact these references Y to directions of flowage are merely for the purpose of assisting the mind to arrive at a proper conception of the invention and when this is accomplished the mere relative direction of flowage becomes of minor importance in comparison` with the general Adistribution and final arrangement of the whole body of metal within the portion of the tube treated.

This improvement may best be understood by recourse to the drawings accompanying and forming a part of this specification and wherein i F Figure 1 is an enlarged elevational view of a tube end u'ndergoing thread formation, this is broken away in a longitudinal line and shown in section with portions of the inner and outer tools in their co-operative relation. Fig. 2 is a view showing in side elevation a threaded tube end, a portionof its wall being broken through for exhibiting its thickness; and Fig. 3 is a perspective view of a tool or device which may be used in practicing the present improvement, parts of this are illustrated as broken away for showing the relative portions of the parts and their mode of operation, a section of tubing is shown in the bite of the tools, This tool is made the subject ofvmy application, Serial No. 277,828 filed September 11, 1905, for threading tool.

The drawings herein are for the purpose of illustration only and are not to be considered as excluding other aids or assistants in practicing this improvement.

lt will be seen by reference to Figs, 1 and 2 that a tube 7, in being provided with 'a taper thread 8, -is gradually reduced in diameter, the thread helix is given a conical disposition, and the tube wall is tapered; the

thread forging action will impart these formations substantially concurrently and as results of the same operation. The thread forming groove 9, see more particularly Fig. l, gradually increases in depth, that is its bottorn portion 10'is brought gradually nearer to the axis of the tube, as will be apparent from a comparison of the respective convolutions of the groove.' The apex 11 of the thread gradually rises above the bottom portion 10 of the groove which also marks the root of the thread, it will be seen that the line 12 marking the apex of the thread indicates a taper to the axial line 13, but a less taper than the line 14 marking the line of the thread root and the bottom of the groove. These lines are not carried out in Fig. l to the region of the tools since to do so wouldl tend to confuse other lines to be hereinafter referred to, and also region is not completed.

During the treatment to which the tube is subjected vthere is an action upon the tube wall at the region of working in the nature of an inward translation of the metal thereof. Of course there is at the same time cooperative treatment proceeding upon both faces of such translated portion, yet for the purpose of this portion of the description such term appears to be adequate. As the tube wall is forced inwardly the crest or apex of the thread is raised and the entering in of the rolls', which may be used in carrying out the treatment, in excess of their ability to build up the thread and swage the tube wall into a taper will displace metal and by the co-operative treatment carried-on at the other side of the tube wall, this'displaced metal will, in its owage, be directed to such a position that it will build up the tube wall at the bottom of the thread forming ve. The thread is forged up -from the normal plane ofthe translated portion, and at and beyond the point or line where the side faces of adjacent convolutions of the thread join, formingthe bottom of the thread groove, the metal is forged up in the opposite direction from such plane; the forged-up metal upon one side of the tube wall constituting a thread, and the forged-up metal upon th'e other side thereof to its disposition,

'form of thread has because the thread at Asuch constituting, owing.

essere a reinforce for the metal sustaining the bottom of the thread forming groove.

ln Fig. 1 it will be seen that the tube wall is acted upon by an outer and an inner tool, 20 and 2l respectively; the outer tool being in the present instance in the form of aroller and having upon it a number of tools 23, 24 and 25. The tool 23 in the present instance is shown as having a rounding workingiace 26 for preliminarily breaking down the metal, and it will be this tool which is largely instrumental in the swaging or tapering of the tube wall, which has above been referred to `as a translation of the metal, or a portion of the wall. rlhis tool is also provided with faces 27 which are disposed approximately upon an angle of 60 degrees one` to the other', this being the angle which has been selected for the thread illustrated herein. The tool 24 is shown as having a rounding crest 28 and -is of slightly larger diameter than the tool 23, such crest, however, extending through a less arc than that of the crest 26, and such tool is shown as provided with faces groove. sponding to `shape of the crest 30 .and of the faces 32 between the giving the shape to the bottom of several tools are for the groove and the apex of the thread approximately corresponding to the Briggs standard pipe thread. This been arbitrarily selected for this illustration, and such thread `is a standard. The inner tool 21 is in the present instance a member-having a screw threaded exterior; it having the pitch of the contemplated thread but the faces of its convolutions are shown at a different angle, in the present instance at an angle of 50 degrees. It will be seen'that the apex 35 of the working face of the inner member is slightly rounding, and that the faces 36 are disposed at an angle of about 50 degrees one to the other.

In bringing the tols together for operation the faces 32 will be disposed above the faces35 in a radial line. As the metal is broken down or swaged into position by the -first tool 23 the vwall of the metal between the faces 27 and lthe apexes 35 will be pinched, the metal below the face 26 will be forced down and there being regions of support afforded the inner faces 31 of the wall of the tube at the apexes 32 and the portions of the faces 37 adjacent thereto the metal will be prevented from being displaced at these regions of support; but the translation o r swaging in ofthe tube wall against these regions of support will vcause a flowage outward for the upbuilding of the thread, and since it will enter the metal in excess of its ability to forge up the crest of the thread and swage in or taper the tube, the excess metal will flow downwardly toward the region devoid of'support indicated by 40. The next tool 24 will by its face 28 continue the downward displacement of the metal, and the faces 29 will carry forward the operation of fashioning the thread faces. The displacement and forging lwill continue as above alluded to, and the next tool will by its face 30 complete the bottom of the thread forming groove and its faces 31 will finish the faces of the thread convolutions. The pressure exerting force in the directions indicated at 4l will have a tendency to pinch CII 4it interiorly, the taper being produced entirely by upraising of the crest or apex of the thread. The tendency of the faces 26, 28Vand .30 are to stretch out and draw the metal, attenuating the same, but the effect of the other faces in cooperation with the inner formingtool is to induce the ilowage of other metal tow'ard such region and build it up so that the displacement is compensated for.

that the lines 50, y 5 degrees one to the other. It will thus be seen that the working faces diverge toward the open space 40 and pinch the metal toward such region devoid of support.

It is immaterial whether or not the apex of the thread built up so long as the In cutting a thread the metal is removed from a spirally disposed groove, and when forming pipe threads the taper, which is universally given the thread is produced bringing the dies gradually toward the axis of the tube, there is no appreciable swaging in oi the wall of the tube and tapering cutting away the metal.

2 it Will be seen that the line 60 indicates the line of the outer face 38 of the portion of the tube 7 which has not been acted upon, and the line (il indicates the bottom of the thread forming groove at about its last convolution, which it will be seen is at a ing of the thickness illustrated in Fig. 2 since the height of the thread indicated between the lines 61 and 62 is about equal to the radial thickness of the tube wall and suiiicient metal would not be left below the bottom of the thread forming groove to sustain even the action of the cutting dies in forming such thread, and considering the distance between the lines and 6]., showing the amount of reduction of the bottom of last convolution of the groove from the outer face of the tube wall, it will be seen that metal of at least the thickness indicated between the lines 60 and 63 would be necessary for use in a tube having cut threads of similar height and taper to those illustrated in Fig. 2. The taper given in present practice for pipe threads is about 3/4of an inch to the foot, and that is the taper that has been illustrated inFigs. l. and 2. It will be seen that not only is the thread given a conical disposition; but the tube wall itself is also given a conical disposition.

This present improvement does not corrugate the walls of the tubing as such term corrugation generally implies when applied to a metal; although in the corrugation perse of a piece of sheet metal there is an amount of molecular reorganization at the crests of the bends, I

and the action of the produce a certain corrugating tools doubtless will arrow 42 for the portion is forged so that it is redistributed. Ms forged or built up upon the outside for forming the thread and inwardly' for forming a reinforce. by its translation is given a conical formation and such tube wall'i`s `moved inwardly in excess of the conical surface described by the summit of the thread in its series of convolutions in the completed taper thread. The wall is translated into a cone more obtuse than is the finished product. The change in fected by raising the thread hlgher toward the smaller summit of each corrugatlon upon the other side of the tube has reinforcing metal forged-up upon it. And after having so distinguished from corrugation it is believed that no confusion can exist. From the apex or crest radially inward solid metal is presented of greater thickness than the original thickness of the tube wall, and from the bottom of the thread forming tool radially inward solid metal is presented of at least the thickness of the original tube wall, and whereas in the corrugating of metal the metal upon the outer face of each crest of corrugation is somewhat stretched, with its incident thinning of the metal and the ing that in some instances the metal below the bottom of the thread forming groove might be thinner than the original tube wall. thickness, yet owing to the forging and Working treatment to which it is subjected it will not have been weakened by the operation; but on the contrary have been strengthened.

1t will be noticed, more particularly in Fig. l, that the convolulious of the thread at the left hand side have concave apexes, there being raised portions 65 at each side of the depressed central portion 66. This is due to the forgirn.r or working action of the faces of the tools, and as the thread proceeds convolution by convolulion toward the right hand it will be seen that the groo've becomes deeper and the thread becomes higher and the apex narrower and less concave until finally the thread is given its finished apex.

Although this present improvement may be practiced by the use of various .instrurlxenta-lities, yet the deviceillustrated in Fig. 3 is particularly useful in this regard This is illustrated as embodied in a device which may take the form of a tool, that is, such a device as may be carried from place to place by a workman in his kit of tools. The working portions are illustrated housed by `a framing or casing member 70,

amount of working of the metal; but having an interiorly screw threaded hub 71, and also The tube wall l compacted at similarly situated regions. vltven assum-y having av'screw threaded connection with a cap portion i the cam face 87 with 4 ed hub 71, and which shaft is shown as having fast upon` are mounted on andere thinner portion before referred to between the sheave andthe spindle toward the outer side of the head, and will bring a thicker portion betweenthe spindle and the portion of the sheave toward the center of the head, which will bring such thicker portion of the eccentric between the body portion of the roller which is in engagement with the work, and the spindle and press it into the work.

The threading operation will be commenced at a point inward of the end of the tube, and be advanced toward such end, the tools running off oi the thread, the inner forming member screwing out o f the groove 90., which has a spiral formation. l It will be observed that in ,employing an instrumentality such4 for instance as that illustrated in Fig. 3 there will be a concurrent action of several rolls upon various portions of the tube walls and each portion oi the tube acted upon will be subjected to the consecutive action oi each oi the tools, for instance if there are nine tools employed each portion ofthe thread will be subjected to the action of the, ninetools, which will produce a consecutive action and forming thereby producing a better finish and a more compact qualityv of metal, not only ,in the thread but in the forged-up metal at and below the bottom of the thread forming gY0Ve In the foregoing description it has been found convenient ,to employthe terms up and downH particularly in the description of the operation-as carried out and illustrated in Fig. 1. This'as will beseen has reference to the position of the drawing upon the sheet,

72, which twoI portions vtogether house the co-operative working parts. The cap portion is shown as provided with a number of openings 7 3, leaving intermediate arm-like portions 474, the f screw threaded hub 75 is Ilongitudinally slotted andthe arms are resilient, such hub is shown as having a taper thread so that when a nut 760 is screwed up' upon it it will press against a section of tubing '7 and clamp the same in. position for treatment, it thereby constituting, as it werefa chuck. The inner and outer forming tools are carried by a tool carrier or head 76 having fast with ita screw threaded shaft 77 engaging with the screw threadit a head 78 having sockets for receiving a suitable barA for rotating the tool'carrier. The inner forming tool 21 is shown as having a screw thread 79 .upon it which is ofthe same pitch as the thread upon the shaft 77. ln this illustration there is shown. a structure which will have three sets of outer forming tools for co-operation with the inner forming tool in the production of a screw thread.

ln the drawings Fig. 3 shows but two sets of tools, one such set having been omitted, due to breaking away parts of the device for showing its internal construction. Each of these is illustrated as comprising a body portion 80 which might be designated as a roller, and'having upon it the tool members 23, 24 and 25. Upon the rotation of the shaft 77 the inner forming tool will be rotated upon its axis, and the various outer forming tools willy be revolved about such axis, which will approximate the axis of the tube being worked upon. The tool carrier is shown as comprising a pair oi plates 81 and 82, which are bored through f or formintend to limit himself the outer perimeter of the tube and raising and spiing bearings for the spindles 83 upon which the forming rally building up the inner side of the tube at-the bottools are mounted, such spindles will be held in place tom of the thread groove, since it would be within the by some suitable means. purview of this improvement to reverse the order and i make couplings for instancehaving a forged upthread upon the inside and a forged-up groove-reinforce upon the outer side. i

Having described my,invention 1 claim:

'1. 'Ihat rt of forming pipe threads which consists of applying inward pressure upon the outside of the pipe on a plurality of pairs of planes angularly disposed one to the other for forming the sides of a plurality of convolutionsof the thread and a plurality of convolutions of the thread forming groove, and concurrently applying outward pressure to a region radially inward of the apex of each thread convolution being acted upon from the outside at two planes angularly disposed one to the other andleaving the Aregion radially inwardpf the bottom of the thread forming groove withoutsupport to thereby induce flowage towards such region for thickening the tube wall below the Upon each spindle is mounted an eccentric member 84, that is, it is of a general cylindrical formation, and' has an eccentrically disposed bore forming a working fit with the spindle, and is provided in the central portion with a flange 85. The respective forming tools the eccentrics and on one side of the ilanges with a working fit, and at the other side o f each flange a sheave 86 will be mounted on each of the eccentrics. These sheaves and eccentrics are for cooperation with suitable cam iac for bringing the tools to their working position, and after they have been' brought to such working position for gradually pressing them toward the center of the ytube for producing the desired taper upon the screw threaded portion. It will be seen that the inner face of the casing consti' tutes a cam of conical formation, it having an angular face 87 and an angular face 88 at a more acute angle to its axis. The face 87 is for engaging the sheaves 86 as they are moved axially during their revolution incident to the axial movement of the tool carrier head upon the rotation oi its shaft 77 The engagement of the face 89 of the sheave will cause it to press upon the eccentric 82 which will squeeze the eccentric around so that the inner portion will be advanced in the direction of the arrow, which is the direction oi rotation oi the sheave by virtue of its engagement with the face 87, the head moving in the direction of the arrow upon it. This will bring the spiral path.

tion which consists in applying pressure to the outside of the tube along a spiral path byl a series of forming faces for shapingthe respective side faces of a pair of adjacent convolutions of a screw thread, such forming faces being joined for shaping the groove, and concurrently applying pressure to the inside of the tube along a spiral path disposed radially inward of the apex of the thread and at the same time permitting the unobstructed ilowage of the metal inwardly below the bottom of said thread forming groove and thereby forming a reinforcing crest.

3. The art of pipe thread formation which consists ln applying pressure to the outer side of a tube wall upon a plurality of planes angularly disposed to the radius of tbc tube and pressing a spiral groove in the said outer side of and is not intended as a limitation. Nor does applicant to the raising of threads upon l bottom of said groove and cohtinulngsuch treatment in a' 120 2. That improvement in the art of pipe thread fornitithe tube wall, and during such pressurel upon the outer side of said tube wall applying pressure to the inner side of the sameA radially inward of the apex of the thread being formed and forming a spira] groove in the innerside of said wail, such grooves corrugating the tube wall, and by the co-operation of such pressures concurrently' with such corrugation building up a crest upon the summits of the corrugations upon the outer and the inner sides of the tube, the crest upon the outer side `forming; the apex of the thread and the crest upon Athe inner side forming. 10

reinforce inwardly of the bottom of the thread forming groove.

'Signed at Nos, 9 to 15 Murra-y street, New York, N. Y., this 16th day of March, 1906.

' CHARLES L. CUMMINGS. Witnesses:

Crus. LYON RssEriL, FRED J. Doma, 

